Nitride films with improved etch selectivity for 3D NAND integration

Abstract

A method for depositing a nitride layer over an oxide layer to form an oxide-nitride stack is provided. The method includes supplying an inert gas to a plasma enhanced chemical vapor deposition (PECVD) reactor that supports a substrate having said oxide layer. Then, providing power to an electrode of the PECVD reactor, where the power is configured to strike a plasma. Then, flowing reactant gases into the PECVD reactor. The reactant gases include a first percentage by volume of ammonia (NH3), a second percentage by volume of nitrogen (N2), a third percentage by volume of silane (SiH4) and a fourth percentage by volume of an oxidizer. The fourth percentage by volume of said oxidizer is at least 0.5 percent by volume and less than about 8 percent by volume. Then, continuing to flow the reactant gases into the PECVD reactor until the nitride layer is determined to achieve a target thickness over the oxide layer.

What is claimed is: 
     
       1. A method for depositing a nitride layer over an oxide layer to form an oxide-nitride stack, comprising:
 supplying an inert gas to a plasma enhanced chemical vapor deposition (PECVD) reactor that supports a substrate having said oxide layer; 
 providing power to an electrode of the PECVD reactor, the power is configured to strike a plasma; 
 flowing reactant gases into the PECVD reactor, the reactant gases include a first percentage by volume of ammonia (NH3), a second percentage by volume of nitrogen (N2), a third percentage by volume of silane (SiH4) and a fourth percentage by volume of an oxidizer, wherein the fourth percentage by volume of said oxidizer is at least 0.5 percent by volume and less than about 8 percent by volume; 
 continuing to flow the reactant gases into the PECVD reactor until the nitride layer is determined to achieve a target thickness over the oxide layer. 
 
     
     
       2. The method of  claim 1 , wherein the third percentage by volume of said silane (SiH4) is about the same as the fourth percentage by volume of said oxidizer or slightly lower. 
     
     
       3. The method of  claim 2 , wherein the first percentage by volume of ammonia (NH3) is about 50%, the second percentage by volume of the nitrogen (N2) is about 45%, the third percentage by volume of the silane (SiH4) is about 2% and the fourth percentage by volume of the oxidizer is about 3%. 
     
     
       4. The method of  claim 1 , further comprising,
 reducing a power level of the power supplied to the PECVD reactor for when the oxidizer is included as the fourth percentage by volume of the reactant gases used for depositing the nitride layer. 
 
     
     
       5. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer assists in reducing hydrogen content in the nitride layer. 
     
     
       6. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer increases a dry etch rate of said nitride layer. 
     
     
       7. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer increases a deposition rate of said nitride layer. 
     
     
       8. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer reduces a refractive index of said nitride layer. 
     
     
       9. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer reduces a stress MPa of the nitride layer. 
     
     
       10. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer reduces in plane displacement (IPD) of the nitride layer. 
     
     
       11. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer improves overlay control of the oxide-nitride stack. 
     
     
       12. The method of  claim 1 , wherein including the fourth percentage by volume of said oxidizer reduces non-uniformity of said nitride layer. 
     
     
       13. The method of  claim 1 , wherein the fourth percentage by volume of said oxidizer is tunable to be between about 0.5 percent by volume and less than about 8 percent by volume. 
     
     
       14. The method of  claim 1 , wherein the oxidizer is one of oxygen (O2), carbon dioxide (CO2), or nitrous oxide (N2O). 
     
     
       15. The method of  claim 1 , wherein the oxide-nitride stack includes multiple stacks of said oxide layer and said nitride layer, wherein each said nitride layer is formed using said oxidizer. 
     
     
       16. The method of  claim 15 , wherein the multiple stacks of said oxide layer and said nitride layer are used in fabricating a 3D-NAND memory device.